Maar-diatreme infill features recorded in borehole imaging

Oriented borehole images recorded with an ultrasonic acoustic televiewer and continuous coring recovery has allowed the characterization of different facies and volcanic processes involved in the infill of a maar-diatreme volcano type. Maar-diatremes are associated with strong explosions throughout most of their development, focused along feeder dikes and generally attributed to magma-water interaction. In the case study of Camp dels Ninots maar-diatreme (Girona, Spain) we have recognized four facies types located in the center of the maar-diatreme: volcanic ash, phreatomagmatic breccia with lithics and juveniles, vesicular pyroclasts (scoria), massive basalt or welded pyroclastic fragments. Ultrasonic televiewer images allow to characterize the different volcanic facies, since they display a different degree of reflectivity and textures. Other features such as fracturing and grain size can be directly measured on the images.Projects 2014-100575 from Departament de Cultura de and SGR2014-901 from AGAUR (both from Generalitat de Catalunya) financed the drilling campaigns.Peer Reviewe

Responses to salt stress in Juncus acutus and J. maritimus during seed germination and vegetative plant growth

[EN] Responses to increasing salinity, during seed germination and vegetative plant growth, were studied in two related species of Juncus, J. maritimus and J. acutus. In both species, germination was optimal in the absence of salt, reduced by about 50% in the presence of 200 mM NaCl, and completely inhibited by NaCl concentrations above 300 mM. Previous exposure of the seeds to salt, up to 500 mM NaCl, did not affect the germination capacity in J. acutus, and clearly enhanced it in J. maritimus. A concentration-dependent inhibition of plant growth was observed in the presence of NaCl for both species, together with the parallel accumulation of sodium ions in the leaves, as determined by cation exchange HPLC. Regarding the levels of divalent cations, in J. acutus Ca2+ and Mg2+ increased up to about two-fold in plants treated with 500 mM NaCl, as compared to control plants, whereas in J. maritimus they were three-to four-fold higher than in J. acutus in the absence of salt, and did not change significantly with increasing NaCl concentrations. These results suggest that Ca2+ and Mg2+ participate in defence mechanisms against salt stress, which would be constitutive in J. maritimus and salt-inducible in J. acutus.Boscaiu Neagu, MT.; Ballesteros Amat, G.; Naranjo Olivero, MA.; Vicente Meana, Ó.; Boira Tortajada, H. (2011). Responses to salt stress in Juncus acutus and J. maritimus during seed germination and vegetative plant growth. Plant Biosystems. 145(4):770-777. doi:10.1080/11263504.2011.628446S770777145

Center of mass, spin supplementary conditions, and the momentum of spinning particles

We discuss the problem of defining the center of mass in general relativity and the so-called spin supplementary condition. The different spin conditions in the literature, their physical significance, and the momentum-velocity relation for each of them are analyzed in depth. The reason for the non-parallelism between the velocity and the momentum, and the concept of "hidden momentum", are dissected. It is argued that the different solutions allowed by the different spin conditions are equally valid descriptions for the motion of a given test body, and their equivalence is shown to dipole order in curved spacetime. These different descriptions are compared in simple examples.Comment: 45 pages, 7 figures. Some minor improvements, typos fixed, signs in some expressions corrected. Matches the published version. Published as part of the book "Equations of Motion in Relativistic Gravity", D. Puetzfeld et al. (eds.), Fundamental Theories of Physics 179, Springer, 201

Eruptive evolution and 3D geological modeling of Camp dels Ninots maar-diatreme (Catalonia) through continuous intra-crater drill coring

Camp dels Ninots is a mixed hard-soft maar-diatreme located in the Catalan Volcanic Zone (NE of Iberia), in which intra-maar lake sediments have preserved one of the most remarkable Pliocene fossil records in Europe. Geophysical surveys combined with the geological map and 11 boreholes, including two new continuous intra-crater drill cores, have enabled the construction of a 3D geological model of this maar-diatreme and its basement. The formation of this maar-diatreme started with a vent-opening phreatomagmatic explosion at the intersection between a regional fault and the Paleozoic groundwater level at a depth of 210 m. We infer and calculate the geometry, dip direction and dip angle of this regional fault. During the eruption, mixed Strombolian and phreatomagmatic episodes occurred, forming the tuff ring and filling the diatreme with minimum estimated volumes of 0.012 and 0.004 km3, respectively. The diatreme infill is composed of three main lithofacies that include tuff-breccias, welded scoriae, and mafic intrusions into the phreatomagmatic breccias. Thus, the stratigraphy of the diatreme succession suggests a progression of explosive events from deeper to shallower zones with short lateral migration of explosion vents, which control its final morphology, without evidence for significant deep enlargement of the diatreme during the later phases. This generated a wide funnel-shaped with low diatreme wall angles that differs from kimberlite pipes with great depths and sharp slope geometries. Hence, such 3D geological model helps to understand the complex architecture of maar-diatreme structures, highlighting the lack of geological modeling of this type of monogenetic system.We would like to thank the landowners, especially Mr. Jaume (Met), for their permission and help to work in the area, and the Town Council of Caldes de Malavella. We also would like to the Departament de Cultura of the Generalitat de Catalunya for the economic funding of the drill coring campaign under the project CLT009/18/00052. This study was partially funded by the project of the Spanish Government and the SGR2017-859 and SGR-2017-1666 projects of the Generalitat de Catalunya. X. Bolós was funded by a UNAM-DGAPA postdoctoral fellowship (2016–2018). O. Oms is part of SGR-2017-1666 Research Group of the Generalitat de Catalunya. B. Gómez de Soler and G. Campeny are funded by the CERCA Programme/Generalitat de Catalunya. The Institut Català de Paleoecologia Humana i Evolució Social (IPHES-CERCA) has received financial support from the Spanish Ministry of Science and Innovation through the ‘María de Maeztu’ program for Units of Excellence (CEX2019-000945-M).Peer reviewe

Technical requirements of a social networking platform for senior citizens.

Feeling an integrative part of a social community adds to the quality of life. Elderly people who find it more difficult to actively join activities are often threatened by isolation. Social networking can enable communication and sharing activities makes it easier to set up and maintain contacts. This paper describes the development of a social networking platform and activities like gaming and exergaming all of which aim to facilitate social interaction. It reports on the particular challenges that need to be addressed when creating a social networking platform specially designed to meet the needs of the elderly